Low evaporative emissions integrated air fuel module

ABSTRACT

An integrated air fuel module ( 10 ) for an internal combustion engine reduces or eliminates the escape of hydrocarbon evaporative emissions from the integrated air fuel module ( 10 ) system, sub systems and components. The integrated air fuel module ( 10 ) includes containment means ( 34 ), such as a valve ( 34 ) or carbon adsorber, that blocks the escape of evaporated hydrocarbon emissions from the air inlet ( 16 ) of an engine during engine off conditions. The module ( 10 ) provides a reduced number of potential external hydrocarbon leak and permeation paths to the surrounding atmosphere. Preferred geometries of the intake manifold ( 12 ) in the module ( 10 ) with the internal integration of other normally external systems, such as fuel injection ( 60 ) and positive crankcase ventilation ( 50 ) systems, accomplish the containment of evaporative emissions within or entering the air fuel module ( 10 ) between engine operating periods when the engine is shut down.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication No. 60/149,142, filed Aug. 16, 1999.

TECHNICAL FIELD

This invention relates to control of engine evaporative emissions ofhydrocarbons and to a low emission integrated air fuel module capable ofcontaining such emissions.

BACKGROUND OF THE INVENTION

Automobile manufacturers have gone to great lengths to reduce emissionscreated by the vehicles they manufacture. Many sources of emissions havebeen pursued. The two major sources of emissions are the exhaustemissions (or ‘tail pipe emissions’) and the hydrocarbon or unburnedfuel that evaporate from other sites on the vehicle (or ‘evaporativeemissions’). In today's vehicles, fuel tanks are vented through carboncanisters so that hydrocarbons are removed from the air escaping fromthe tank due to pressure differentials. These evaporative emissions arestored until they can be pulled into the engine and consumed. This typeof system is very effective at stopping hydrocarbon emissions fromescaping from the fuel tank system.

There are sources other than the fuel tank that can contribute to thehydrocarbon evaporative emissions of a vehicle. One such source is the‘breathing’ of the air induction system during hot soak and diurnaltemperature cycling. Unburned fuel resident in the intake system afterengine shutdown evaporates into the air in the system. Air exchanges,between the air induction system and the atmosphere, carry theseevaporated hydrocarbon emissions into the atmosphere. Activated charcoalor ‘carbon adsorbers’ have previously been installed in air cleanerhousings to reduce these hydrocarbon emissions. The carbon adsorberdraws in and holds the hydrocarbons until the engine is started and theair flow past the adsorber pulls the hydrocarbons back into the engineand purges the adsorber.

Another common source of hydrocarbon emmissions is seal leakage of bothhigh pressure and low pressure fuel components and systems. Current fueldelivery systems contain many such potential leak paths. These includeO-rings, injector and fuel rail interfaces, fuel regulator diaphragm,end plugs, fuel rail inlet and outlet, service valve, and crankcaseventilation system interfaces and joints. Each of these locations hasthe potential of leaking emissions to the surrounding environment.

A third common source of hydrocarbon emissions to the atmosphere ispermeation of the fuel through the materials of the system. Hydrocarbonscan permeate most composite and elastomer materials commonly used in theautomotive engine environment. Small amounts of hydrocarbons thereforeleak through the walls of composite components in the system and throughthe elastomer O-rings and seals at the interfaces in the system. Thisleakage is increased with higher fuel pressures driving the hydrocarbonsout through the walls.

The above contributors are generally small in relation to the totalevaporative emissions of the vehicle and automobile manufacturers canmeet the current standards without further development or control.However, in order to meet zero or near zero evaporative emissionsrequirements, engine suppliers and vehicle manufactures will have toreduce the number of leak and permeation sites that can emithydrocarbons.

SUMMARY OF THE INVENTION

The present invention provides an integrated air fuel module for aninternal combustion engine that reduces or eliminates the escape ofhydrocarbon evaporative emissions from the integrated air fuel modulesystem, sub systems and components. The integrated air fuel module ofthe present invention includes containment means, such as a valve orcarbon adsorber, that blocks the escape of evaporated hydrocarbonemissions from the air inlet of an internal combustion engine duringengine off conditions. The module provides a reduced number of potentialexternal hydrocarbon leak and permeation paths to the surroundingatmosphere. Preferred geometries of the intake manifold in the modulewith the internal integration of other normally external systems, suchas fuel injection and positive crankcase ventilation systems, accomplishthe containment of evaporative emissions within or entering the air fuelmodule between engine operating periods when the engine is shut down.

These and other features and advantages of the invention will be morefully understood from the following description of certain specificembodiments of the invention taken together with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a conceptual cross-sectional view of a low evaporativeemissions integrated air fuel module including features according to theinvention;

FIG. 2 is a cross-sectional view showing an exemplary form ofcontainment valve in the module inlet portion; and

FIG. 3 is an exterior pictorial view of a module for a V-8 engineincluding features of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring first to FIG. 1 of the drawings in detail, numeral 10generally indicates an exemplary low evaporative emissions integratedair fuel module for an internal combustion engine, the module includingfeatures according to the invention. Module 10 includes a housing 12internally defining an air system 14. The air system includes in seriesan inlet portion 16 for admitting charge air, a throttle control portion18 having a throttle valve 20 for controlling air flow, a connectingportion 22, or zip tube, for tuning the air flow, an inlet plenum 24 fordistributing and balancing the air flow, and a plurality of intakerunners 26. The runners 26 connect individually with the plenum andconnect the plenum 24 with outlet ports 28 along a cylinder headinterface 30 coplanar with a mounting flange 32 of the housing 12. Therunners 26 and outlet ports 28 distribute the air flow to inlet ports ofan engine, not shown, for intermittent admission to associated cylindersduring operation of the engine.

In accordance with the invention, the inlet portion includes containmentmeans for limiting the escape of evaporative emissions from within theair system through the inlet portion between periods of engineoperation, that is, when the engine is stopped. Air system 14 includesan exemplary embodiment of containment means in the form of acontainment valve 34, shown in further detail with the inlet portion 16in FIG. 2. Valve 34 includes a pivotable edge mounted flapper type valveelement 36 including a sharp edged sealing portion 38 engagable, whenthe valve is closed, with a valve seat 40 of an air inlet 42 in theinlet portion 16.

A variable force spring 44 engages the valve element to bias the valvein a closing direction. The spring 44 may be a curved spring steel tapeshaped similarly to a steel rule tape but used as a spring. In theclosed position shown in solid lines, the spring is positioned to exerta maximum force to hold the valve element 36 firmly against the valveseat 40. When the valve is opened, the spring flattens and bends easilyto allow opening of the valve against a lower spring force.

An actuator 46 is provided for pivoting the valve element to the openposition shown in dashed lines in FIGS. 1 and 2. Any suitable form ofactuator may be used which is responsive to signals indicating operatingand shutdown conditions of the engine. The illustrated actuatorrepresents a vacuum motor 46 that opens the valve in response to vacuumin the air system 14, which indicates that the engine is in operation.The vacuum motor 46 allows the valve to be closed and held in place bythe spring 44 when loss of vacuum with near ambient pressure in the airsystem indicates that the engine is stopped.

Containment valve 34 and vacuum motor 46 are only exemplary of the manyforms of suitable containment means and actuators which could be usedwithin the scope of the invention. Any suitable electric, pneumatic orfluid actuator might be used with appropriate controls if needed.Containment means may include many forms of valves, including pivotingblades, plungers, reed valves and other check valves, as examples.Instead of valves, carbon adsorbers may provide adequate containment ofevaporative emissions and could be used as containment means within thescope of the invention.

In accordance with the invention, the air fuel module 10 also includes apositive crankcase ventilation (PCV) system 50, which is primarilycontained within the air system 14 of the housing 12. The PCV system 50includes a ventilation inflow passage 52 that connects the air inletportion between the containment valve 34 and the throttle valve 20 witha ventilation outlet 54 at the cylinder head interface 30 of thehousing. A ventilation outflow passage 56 is also provided which extendsfrom the interface 30 to the air system 14 downstream of the throttlevalve 20. Passages 52, 56 are defined by walls that are primarilycontained within the housing defined air system 14 of the module 10.When the module 10 is installed on an engine, the passages 52, 56,including outlet 54, are connected with the crankcase chamber of theengine for passing ventilation air through the crankcase. A PCV valve 58is located in the ventilation outflow passage 56 to control the flow ofair and crankcase vapors through the PCV system.

In accordance with the invention, the air fuel module 10 furtherincludes a fuel injection system 60 that is primarily contained withinthe air system 14 of the housing 12. Fuel injection system 60 includesone or more fuel rails 62 that extend longitudinally within the housing12. A plurality of fuel injectors 64, generally one for each enginecylinder, are connected with the fuel rail(s) to receive pressurizedfuel supplied from a source external to the module housing 12. The fuelrail(s) 62 and the injectors 64 are mounted entirely within the housing12 and the air system 14 defined by the housing. The injectors arepositioned to spray fuel out through the outlet ports 28 from therunners 26 to mix with air in the intake ports and cylinders of theassociated engine, not shown). Preferably, the mounting locations of theinjectors and all the connections with the fuel rails and of the fuelrails with incoming fuel lines are contained with the air system 14.Thus, any leakage of evaporative emissions from the internal portions ofthe fuel system will be contained within the air system and drawn intothe engine during engine operation.

In addition to potential leakage of evaporative emissions from jointsbetween various elements of the fuel system, the PCV system and backflowof gases from connected engine cylinders and intake ports, additionalemissions may occur by permeation of fuel vapors and the like throughmolded plastic internal walls of the various systems in the housing 12.Thus, a molded housing may require treatment of at least the outer wallsto maintain containment of evaporated hydrocarbons and other substanceswithin the housing when the engine is shut down. Alternatively, thehousing 12, or at least its outer walls, may be made from cast aluminumor other metal having low permeability.

In the embodiment of FIG. 1, the housing 12 is preferably made as aplastic molding in three sections, an entry conduit 66, an uppermanifold 68 and a lower manifold 70. The lower manifold 70 includes themounting interface 30 and the lower portions of the plenum 24 andrunners 26 as well as the components of the fuel injection system 60.The upper manifold 68 includes upper portions of the plenum 24 andrunners 26. The PCV system passages 52, 56 extend into both manifoldsections 68, 70 but the PCV valve 58 is mounted in the upper manifold.The entry conduit 66 is mounted on the upper manifold 68 and isremovable to allow access to service the PCV valve.

Referring particularly to FIG. 3 of the drawings, the air fuel module 72there disclosed further includes within a housing 74, a coolantcrossover 76 having internal passages, not shown, for carrying coolantbetween cylinder banks of an associated V-8 engine. A liquid cooledelectrical alternator 78 is mounted within the crossover 76 and iscooled by coolant in the passages during engine operation. The figurealso shows a side mounted electric throttle control 80 for the internalthrottle valve. The housing 74 is made in two sections, including anupper manifold 82 mounted on a lower manifold 84. The latter includes amounting flange 86 coplanar with the lower interface, not shown, thatmounts on the associated engine cylinder heads. Internally the elementsof the module 72 are essentially similar to those of module 10 in FIG.1.

In operation of an engine having an air fuel module 10 as shown in FIG.1, the containment valve 34 is opened upon starting of the engine, andremains open, allowing the entry of charging air into the module airsystem 14. Vaporized hydrocarbons and other vapors retained in the airsystem are drawn into the engine with the new air charges and burned inthe engine. Any fuel vapors seeping into the air system 14 during engineoperation are likewise drawn into the engine and burned along with thecrankcase vapors flushed out by the PCV system 50, which are drawn fromthe engine crankcase by vacuum in the module downstream of the throttlevalve 20. The inlet air controlled by the throttle valve and includingany added crankcase vapors continues through the manifold connectingportion or zip tube 22 and enters the inlet plenum 24. The air is thendrawn into the individual engine cylinders through the intake runners 26and outlet ports 28 of the module into associated intake ports of theengine. Fuel is added to the incoming air by the fuel injectors 64 thatare part of the fuel injection system 60 enclosed within the air fuelmodule 10. The fuel is sprayed from the module directly into thecylinder head intake ports, not shown, and normally against the intakevalve to assist vaporization.

When the engine is stopped, the spring 44 closes the containment valve34, sealing off the inlet portion 16 of the air system 14. Fuel andother vapors in the air system 14 or entering the system 14 from theassociated engine ports or from the internal PCV and fuel injectionsystems 50, are thus contained within the air system 14 and preventedfrom escaping into the atmosphere. Restarting of the engine again drawsthe stored vapors into the engine and disposes of them by burning.

While the invention has been described by reference to certain preferredembodiments, it should be understood that numerous changes could be madewithin the spirit and scope of the inventive concepts described.Accordingly, it is intended that the invention not be limited to thedisclosed embodiments, but that it have the full scope permitted by thelanguage of the following claims.

What is claimed is:
 1. An air fuel module (10) for an internalcombustion engine intended for containment of evaporative emissions inan induction system of the engine between periods of engine operation,said module (10) comprising: a housing (12) internally defining an airsystem (14) including an inlet portion (16) and a plurality of intakerunners (26) connecting with the inlet portion and extending to outletports (28) adapted for connection with associated intake ports of theengine in which fuel is mixed with air from the air system; andcontainment means (34) in said inlet portion (16) of the air system (14)and operative between periods of engine operation to limit the escapethrough the inlet portion (16) of evaporative emissions entering orremaining in the air system (14) after engine shutdown.
 2. An air fuelmodule (10) as in claim 1 wherein said air system (14) includes athrottle control portion (18) having a throttle valve (20), a connectingportion (22) and an inlet plenum (24) all connected in series betweensaid inlet portion (16) and said intake runners (26).
 3. An air fuelmodule (10) as in claim 2 including a PCV system (50) primarilycontained within the air system (14) of said housing (12), the PCVsystem (50) including a ventilation inflow passage (52) connecting theair system (14) upstream of the throttle (20) with a ventilation outlet(54) adapted for connection with a crankcase chamber of an associatedengine and a ventilation outflow passage (56) adapted for connectingsaid crankcase chamber with the air system (14) downstream of thethrottle (20), and a PCV valve (58) in the outflow passage (56) forcontrolling ventilation flow through the PCV system (50), wherebycrankcase vapors within or leaking from the PCV system (50) areessentially contained within the air system (14) and retained by thecontainment means (34) when the engine is shut down.
 4. An air fuelmodule (10) as in claim 1 including a fuel injection system (60)primarily contained within the air system (14) of said housing (12),said fuel injection system (60) including a fuel rail (62) connectedwith a plurality of fuel injectors (64) mounted for injection of fuelspray through the outlet ports (28) of the air system (14) into theassociated engine intake ports, whereby evaporative fuel emissionswithin or leaking from the fuel injection system (60) are essentiallycontained within the air system (14) and retained by the containmentmeans (34) when the engine is shut down.
 5. An air fuel module as inclaim 1 wherein said containment means is a containment valve operableto close the inlet portion of the air system upon engine shutdown and toopen the inlet portion to air inflow upon restarting of the engine. 6.An air fuel module as in claim 5 wherein said containment valve isoperated by an actuator responsive to signals indicating operating andshutdown conditions of the associated engine.
 7. An air fuel module asin claim 6 wherein said actuator includes a vacuum motor connected withthe housing air system and responsive to vacuum in the air system toopen the containment valve, and a spring for closing the valve upon lossof vacuum.
 8. An air fuel module as in claim 7 wherein said springexerts a greater force when the valve is closed than when the valve isopen to maintain secure closure of the valve against escape ofemissions.